PKC monocyte assay

ABSTRACT

The invention features a method for evaluating PKC activity in vascular tissues. The invention also features methods for diagnosing cardiovascular and diabetes related disorders, and for identifying and evaluating treatments for cardiovascular or diabetes related disorders. Methods for identifying and evaluating treatments for aging are also included. The methods include measuring PKC activity in monocytes as a surrogate for PKC activity in other tissues.

RELATED APPLICATIONS

[0001] This application claims the benefit of Provisional ApplicationNo. 60/257,769, filed Dec. 22, 2000, the contents of which areincorporated herein by reference, in their entirety.

BACKGROUND

[0002] Recent studies have identified that hyperglycemia induces de novodiacylglycerol (DAG) synthesis and activates Protein Kinase C (PKC),which leads to many kinds of vascular abnormalities involvingabnormalities of the retina, glomeruli and cardiovascular tissues. Inclinical assessment, measurement of PKC activity in vascular tissues isdesired, but it is not easy to obtain vascular samples from diabeticpatients repeatedly.

SUMMARY OF THE INVENTION

[0003] The inventor has discovered that PKC activity, e.g., PKCβactivity, in mononuclear cells, e.g., monocytes, correlates with PKCactivity in other tissues, e.g., in vascular or cardiovascular tissue(e.g., in retinal, kidney or aorta vascular tissues or heart).Accordingly, the invention features a method of evaluating the level ofPKC activity in a tissue other than monocytes of a subject, e.g., invascular or cardiovascular tissue, e.g., in retinal, kidney or aortavascular tissues or heart. The method includes evaluating the level ofthe PKC activity, e.g., PKC β activity, in mononuclear cells, e.g.,monocytes, of the subject. The level of PKC activity in mononuclearcells is correlated with the level of PKC activity in other tissues,e.g., vascular tissue, e.g., in retinal, kidney or aorta vascular tissueor in heart. The subject can be a human, or any non-human animal, e.g.,a non-human mammal, e.g., rode

[0004] In a preferred embodiment, PKCβ activity is evaluated.

[0005] In a preferred embodiment, the subject is a human.

[0006] In a preferred embodiment, the subject is an experimental animal.

[0007] The invention also features methods of evaluating a subject,e.g., staging of, evaluating the treatment of, or determining if asubject is at risk for (e.g., has a genetic disposition to), has asymptom of, or is afflicted with, a PKC related disorder, e.g., adisorder described herein, e.g., diabetes, diabetes mellitus, Type Idiabetes, Type II diabetes, diabetic retinopathy, proliferative diabeticretinopathy, non-proliferative diabetic retinopathy, diabeticnephropathy, microalbumiuria, proteinuria, renal failure, cardiovasculardisorder, hypertension, atherosclerosis, coronary artery spasm,congestive heart failure, coronary artery disease, valvular disease,arrhythmias, cardiomyopathy, aging, or an aging-related disorder. Themethod includes evaluating the level of PKC activity, e.g., PKC βactivity, in mononuclear cells, e.g., monocytes, of the subject.Optionally, the method also includes comparing the level of the PKCactivity in monocytes of the subject with a standard, e.g., the level ofPKC activity in a control sample, e.g., a non-diabetic subject, a presetvalue, or a basal activity value.

[0008] In some embodiments, the level of the PKC activity in monocytesof a subject correlates with risk of developing a PKC-related disorder,e.g., diabetic retinopathy or another PKC related disorder describedherein. For example, the level of PKC activity in monocytes of a subjectcorrelates with a genetic predisposition to a PKC-related disorder,e.g., retinopathy.

[0009] In a preferred embodiment, PKCβ activity is evaluated.

[0010] In a preferred embodiment, the subject is a human.

[0011] In a preferred embodiment, the subject is an experimental animal.

[0012] In another aspect, the invention features a method of evaluatinga subject for the extent, stage, or severity, of a PKC related disorder,e.g., a disorder described herein, e.g., diabetes, diabetes mellitus,Type I diabetes, Type II diabetes, diabetic retinopathy, proliferativediabetic retinopathy, non-proliferative diabetic retinopathy, diabeticnephropathy, microalbumiuria, proteinuria, renal failure, cardiovasculardisorder, hypertension, atherosclerosis, coronary artery spasm,congestive heart failure, coronary artery disease, valvular disease,arrhythmias, cardiomyopathy, aging, or an aging-related disorder. Themethod includes evaluating the level of PKC activity in monocytes of thesubject and, optionally, comparing the level of the PKC activity inmonocytes of the subject with a standard, e.g., a preset value, thelevel of PKC activity in a control sample or subject, or a basalactivity value. The level of PKC activity in the monocytes iscorrelated, preferably positively, with the extent, stage, or severity,of the PKC related disorder.

[0013] In a preferred embodiment, PKCβ activity is evaluated.

[0014] In a preferred embodiment, the subject is a human.

[0015] In a preferred embodiment, the subject is an experimental animal.

[0016] In another aspect, the invention features methods of evaluatingthe effect of a treatment for a PKC related disorder, e.g., diabetes,diabetes mellitus, Type I diabetes, Type II diabetes, diabeticretinopathy, proliferative diabetic retinopathy, non-proliferativediabetic retinopathy, diabetic nephropathy, microalbumiuria,proteinuria, renal failure, cardiovascular disorder, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease, valvular disease, arrhythmias, cardiomyopathy,aging, or an aging-related disorder, which includes administering atreatment to a subject and measuring PKC activity, e.g., PKC β activity,in the subject's mononuclear cells, e.g., monocytes. The treatment canbe, e.g., administration of a compound, e.g., a protein (e.g., anantibody or a hormone, e.g., insulin), a small molecule, a vaccine, anucleic acid). The subject can be a human, or a non-human animal, e.g.,a rat or a mouse, or an animal model for a disorder described herein,e.g., a NOD mouse and its related strains, BB Rat, Leptin or LeptinReceptor mutant rodents, Zucker Diabetic Fatty (ZDF) Rat, ObeseSpontaneously Hypertensive Rat (SHROB, Koletsky Rat), Wistar Fatty Rat,New Zealand Obese Mouse, NSY Mouse, Goto-Kakizaki Rat, OLETF Rat,JCR:LA-cp Rat, Neonatally Streptozotocin-Induced (n-STZ) Diabetic Rats,Sprague-Dawley rat, Rhesus Monkey, Psammomys obesus (fat sand rat),C57B1/6J Mouse. The level of PKC activity in the monocytes is correlatedwith the effect of the treatment. The method can be used, e.g., toevaluate the effect of an experimental treatment, e.g., an experimentalcompound, or a known treatment, e.g., insulin.

[0017] In a preferred embodiment, PKCβ activity is evaluated.

[0018] In a preferred embodiment, the subject is a human.

[0019] In a preferred embodiment, the subject is an experimental animal.

[0020] In yet another aspect, the invention features a method ofidentifying a compound for treating a PKC related disorder, e.g.,diabetes, diabetes mellitus, Type I diabetes, Type II diabetes, diabeticretinopathy, proliferative diabetic retinopathy, non-proliferativediabetic retinopathy, diabetic nephropathy, microalbumiuria,proteinuria, renal failure, cardiovascular disorder, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease,valvular disease, arrhythmias, cardiomyopathy,aging, or an aging-related disorder. The method includes administering atest compound to a subject, e.g., an animal, e.g., a mouse or a rat, oran animal model for a disorder described herein, and measuring PKCactivity, e.g., PKC β0 activity, in mononuclear cells, e.g., monocytes,of the subject. The level of PKC activity in the monocytes is correlatedwith the effect of the treatment. The method may also optionally includeidentifying a subject in need of a treatment for the PKC relateddisorder, and comparing the PKC activity, e.g., PKC β activity, inmonocytes, after administration of a test compound, to a standard. Acompound for the treatment of the disorder is identified when the PKCactivity after the administration of the compound is altered, e.g.,increased or decreased, as compared to a standard, e.g., a preset value,the level of PKC activity in a control sample, a basal activity value,orthe PKC activity before, or in the absence of, the administration of thecompound.

[0021] In a preferred embodiment, PKCβ activity is evaluated.

[0022] In a preferred embodiment, the subject is a human.

[0023] In a preferred embodiment, the subject is an experimental animal.

[0024] In a preferred embodiment, the method further includes isolatinga compound identified as having an effect on a PKC-related disorder,and, optionally, administering the compound to a subject, e.g., a humansubject having such a disorder

[0025] In another aspect, the invention features a method of identifyinga compound for the treatment of aging or an aging-related disorder in asubject, e.g., an animal. e.g., a mouse or a rat, or an animal model fora disorder described herein. The method includes administering a testcompound to the subject and evaluating a PKC activity, e.g., a PKC βactivity, in monocytes of the subject. The level of PKC activity iscorrelated with the effect of the treatment on the disorder. Preferably,the level of PKC activity is decreased compared to a standard. Acompound for the treatment of aging or an aging-related disorder isidentified when the PKC activity after the administration of thecompound is altered, e.g., increased or decreased, as compared to astandard, e.g., a preset value, the level of PKC activity in a controlsample, a basal activity value, or the PKC activity before, or in theabsence of, the administration of the compound.

[0026] In a preferred embodiment, PKCβ activity is evaluated.

[0027] In a preferred embodiment, the subject is a human.

[0028] In a preferred embodiment, the subject is an experimental animal.

[0029] In a preferred embodiment, the method further includes isolatinga compound identified as having an effect on aging or an aging-relateddisorder, and, optionally, administering the compound to a subject,e.g., a human subject having such a disorder

[0030] In another embodiment, the invention provides a method ofevaluating the effect of a treatment for aging or an aging-relateddisorder on a subject, which includes administering a treatment foraging or an aging-related disorder to a subject, e.g., a human, or anon-human animal, and evaluating the level of PKC activity, e.g., PKC βactivity, in the subject's monocytes.

[0031] In a preferred embodiment, PKCβ activity is evaluated.

[0032] In a preferred embodiment, the subject is a human.

[0033] In a preferred embodiment, the subject is an experimental animal.

[0034] The methods described herein can be used, e.g., to evaluate theeffect of a treatment on PKC activity before, during, and/or afteradministration of a treatment. In some embodiments, the effect of atreatment can be evaluated over time (e.g., over minutes, hours, days,weeks, months) by repeating the evaluation of PKC activity as describedherein. For example, PKC activity can be evaluated one, two, three,four, five, or more times after the initial evaluation of PKC activityin response to treatment. In other embodiments, the treatment can beadministered more than once, and the effect of subsequentadministrations can be evaluated by repeating the evaluation of PKCactivity in mononuclear cells, e.g., monocytes, as described herein.

[0035] The details of one or more embodiments of the invention are setforth in the accompanying drawings and the description below. Otherfeatures, objects, and advantages of the invention will be apparent fromthe description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

[0036]FIG. 1 shows the correlation between blood glucose level and PKCactivity in monocytes.

[0037]FIG. 2 shows the correlation between hemoglobin A1c (HbA1c) leveland PKC activity in monocytes. In the blood, glucose binds irreversiblyto hemoglobin molecules within red blood cells. The amount of glucosethat is bound to hemoglobin is directly tied to the concentration ofglucose in the blood. Thus, measuring the amount of glucose bound tohemoglobin can provide an assessment of average blood sugar controlduring the 60 to 90 days prior to the test. The HbA1c test is the mostcommon test for glycated hemoglobin.

[0038]FIG. 3 shows the correlation between diabetic retinopathy and PKCactivity in diabetic patients.

[0039]FIG. 4 shows the correlation between diabetic nephropathy and PKCactivity in diabetic patients.

DETAILED DESCRIPTION

[0040] Leukocytes, especially monocytes, contain PKC α and β isoforms.PKC activation is associated with monocyte adherence to endothelialcells and with their transendothelial migration. The invention is based,in part, on the discovery that PKC activity in cardiovascular tissues,e.g., in vascular tissues of retina or kidney, of subjects, e.g., normalor diabetic subjects, is correlated with PKC activity, e.g., PKC βactivity, in mononuclear cells, e.g., monocytes.

[0041] Further, the invention is based, in part, on the discovery thatPKC activity, e.g., PKC β activity, is correlated with aging, and withseverity of diabetic complications, e.g., diabetic nephropathy ordiabetic retinopathy.

[0042] Preparation of Mononuclear Cells

[0043] Mononuclear cells can be prepared, e.g., substantially isolatedfrom other blood components, by various methods known in the art. Anexemplary method is described herein below.

[0044] Monocytes of rats and also human control subjects and patientswith diabetes were isolated from blood with anticoagulant of sodiumcitrate. The blood sample was put onto the same volume ofHistopaque-1077 (Sigma) and centrifuged at 400 ×g for 30 minutes at roomtemperature. The layer containing mononuclear cells was transferred to anew tube and washed with phosphate-buffered saline (PBS). Aftercentrifugation at 400 ×g for 10 minutes, cell pellet was suspended witha solution of 144 mM NH4Cl and 17 mM Tris-HCl, pH 7.65 to lyse thecontaminated red blood cells. Mononuclear cells were washed with PBS andused in this study.

[0045] In Situ PKC Activity Assay

[0046] PKC activity assays are known in the art. One type of assayincludes (a) contacting the sample to be evaluated for PKC activity with(i) a substrate molecule capable of accepting a phosphate (e.g. a kinasesubstrate peptide) and (ii) a labeled source of phosphate (e.g., labeledATP, e.g., radiolabeled ATP); and (b) evaluating the amount of labeltransferred to the substrate molecule in the presence of the sample. PKCactivity can be evaluated, e.g., in situ or in vitro, e.g., in acellular or tissue membrane fraction. Exemplary methods are describedherein below.

[0047] Mononuclear cells of human and rats and retina of rats weresuspended in a buffer containig 137 mM NaCl, 4.3 mM KCl, 0.3 nM Na₂HPO₄,0.4 mM KH₂PO₄, 5.5 mM D-Glucose, 10 mM MgCl₂, 1 mM CaCl₂, 25 mMβ-glycerophosphate, and 20 mM HEPES, pH 7.2. The reaction was initiatedby adding solution containing digitonin, substrate peptide, (RKRTLRRL,corresponding to the epidermal growth factor receptor), and γ-³²P-ATP.After 15 minutes incubation at room temperature, the reaction wasterminated with trichloroacetic acid (TCA). An aliquot of the reactionsolution was spotted on a phosphocellulose paper, and the paper waswashed with 75 mM phosphoric acid solution, followed by washing with 75mM sodium phosphate solution to remove residual γ-³²P-ATP. The paper wasput into a scientillation vial and radioactivity of ³²p was assayed byscientillation counter. The paper was put into a scintillation vial andradioactivity of ³²p incorporated into substrate peptide per minute permg of protein, and calculated by the difference between the activity inthe presence of substrate peptide and the activity in the absence of thepeptide.

[0048] PKC Activity in the Membranous Fraction

[0049] After isolating membranous fractions of heart and aorta of rats,PKC activity was measured by its ability to transfer ³²P from γ-³²P-ATPinto specific substrate peptide (same peptide used in the in situ assay)in the presence of Ca²⁺, Phosphatidylserine (PS), and DAG. PKC activitywas calculated by subtracting the nonspecific activity in the absence ofCa²⁺, PS, DAG, and expressed as pmol of ³²P incorporated into substratepeptide per minute per mg of protein.

[0050] Data Analysis

[0051] The differences were analyzed by one way ANOVA test. Linearregression was assessed using a linear fit with Sigma Stat version 2.03statistical software.

[0052] Rat Studies

[0053] Male Sprague-Dawley rats at the age of 6 weeks were used in thisstudy. Diabetic rats were induced by intraperitoneal injection of STZ(60 mg/kg). Some of the STZ-induced diabetic rats were treated withinsulin (insulin pellet, inserted subcutaneously) or oral PKC βinhibitor (LY333531). After 2 weeks, mononuclear cells from bloodsample, heart, aorta and retina were isolated from the rats. PKCactivity in these tissues was measured as described below.

[0054] PKC activities in heart, aorta and retina of rats were tested tocompare with PKC activity in mononuclear cells. As compared to thecontrol rats, PKC activities in heart, aorta and retina were increasedby 42%, 50%, 51%, respectively. PKC activity in rat mononuclear cellswas significantly increased in STZ-induced diabetic rats (56% increase).The increase in PKC activity was restored to the level of control ratsby insulin.

[0055] Human Studies

[0056] PKC activity was measured in monocytes of normal (non-diabetic)human subjects. Monocyte PKC activity was found to decrease with the ageof the subjects. PKC activity in older subjects (age 40 or greater) wassubstantially less than that in younger subjects.

[0057] PKC activity in human monocytes was significantly increased by62% in patients with diabetes compared to control subjects (p<0.05). PKCactivity in human mononuclear cells was significantly correlated withblood glucose level (R=0.462, R²=0.214, p<0.001) (FIG. 1), and withlevels of glycosylated hemoglobin (HbA1c) in the subjects (R=0.547,R²=0.300, p<0.001) (FIG. 2).

[0058] To examine relationships between PKC activity and diabeticcomplications, the diabetic patients were divided into groups accordingto the severity of complications. PKC activity increased with severityof diabetic retinopathy (non-DR; 134±24, non-proliferative-DR; 162±25,proliferative DR; 184±37) (FIG. 3). Also, PKC activity in the group ofdiabetic patients with proliferative retinopathy was significantlyhigher than that in the group of patients without retinopathy (p<0.001).

[0059] Patients were also classified according to severity of diabeticnephropathy. PKC activity was increased in correlation with the severityof the nephropathy (without microalbumiuria; 145 ±35, withmicroalbumiuria; 164±31, with proteinuria and/or renal failure; 192±19),and a significant difference was identified between the diabetic groupwithout microalbumiuria and the group with proteinuria and/or renalfailure (p=0.003) (FIG. 4). Analysis of the data also indicates that PKCactivity in monocytes has significance with regard to the genetics ofdisease, e.g., in retinopathy. PKC activity correlated with adisposition (which can be, e.g., a genetic predisposition), to earlierdevelopment of PKC related disease, e.g., retinopathy.

[0060] As shown above, the level of PKC activity in monocytes wascorrelated with age in normal subjects, suggesting that monocyte PKCactivity can be used as an indicator for aging or symptoms of aging.Therefore, monocyte PKC activity may be used as an assay in thediagnosis, and in the identification and evaluation of treatments, foraging or aging related disorders and symptoms.

[0061] Also, PKC activity in mononuclear cells was correlated with thatin heart, aorta, and retinal vasculature, indicating that PKC activityin mononuclear cells can be used as a surrogate marker for PKCactivation in vascular and heart tissues. Therefore, monocyte PKCactivity can be used as an assay for the diagnosis (including diagnosisof disease stage, severity, or predisposition) of cardiovasculardisorders, and the identification and evaluation of treatment forcardiovascular disorders. Examples of cardiovascular disorders ordisorders involving the heart include, but are not limited to, adisease, disorder, or state involving the cardiovascular system, e.g.,the heart, the blood vessels, and/or the blood. A cardiovasculardisorder can be caused by an imbalance in arterial pressure, amalfunction of the heart, or an occlusion of a blood vessel, e.g., by athrombus. Examples of such disorders include retinopathy, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease, valvular disease, arrhythmias, andcardiomyopathies.

[0062] In addition, PKC activity in mononuclear cells of human subjectswas correlated with glycemic control and associated with the severity ofdiabetic complications, suggesting that PKC activity in monocytes canserve as a surrogate for evaluation of diabetic complications. Examplesof diabetic complications include, but are not limited to, diabeticnephropathy, diabetic retinopathy, altered or deficient blood glucoselevel or glycosylated hemoglobin.

[0063] A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A method of evaluating a protein kinase C (PKC)activity in a tissue other than monocytes of a subject, the methodcomprising: evaluating the level of the PKC activity in monocytes of thesubject, the level of PKC activity in the monocytes being correlated tothe level of PKC activity in a tissue other than monocytes.
 2. Themethod of claim 1, wherein the PKC activity is PKC β activity.
 3. Themethod of claim 1, wherein the tissue is cardiovascular tissue.
 4. Themethod of claim 3, wherein the cardiovascular tissue is retinal, kidneyor aorta vascular tissue or heart.
 5. The method of claim 1, wherein thesubject is a human.
 6. The method of claim 1, wherein the subject is anexperimental animal.
 7. A method of determining if a subject is at riskfor or has a PKC related disorder, the method comprising: evaluating thelevel of PKC activity in monocytes of the subject; optionally comparingthe level of the PKC activity in monocytes of the subject with astandard, thereby determining if the subject has a symptom of a PKCrelated disorder.
 8. The method of claim 7, wherein the PKC activity isPKC β activity.
 9. The method of claim 7, wherein the disorder isdiabetes.
 10. The method of claim 7, wherein the disorder is diabeticretinopathy.
 11. The method of claim 7, wherein the disorder is diabeticnephropathy.
 12. The method of claim 7, wherein the disorder is acardiovascular disorder.
 13. The method of claim 7, wherein the subjectis a human.
 14. The method of claim 7, wherein the subject is anexperimental animal.
 15. The method of claim 7, wherein the disorder isselected from the group consisting of: diabetes mellitus, Type Idiabetes, Type II diabetes, diabetic retinopathy, proliferative diabeticretinopathy, non-proliferative diabetic retinopathy, diabeticnephropathy, microalbumiuria, proteinuria, renal failure, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease, valvular disease, arrhythmias, andcardiomyopathy.
 16. A method of evaluating a subject for the extent,stage, or severity, of a PKC related disorder comprising: evaluating thelevel of PKC activity in monocytes of the subject; and optionallycomparing the level of the PKC activity in monocytes of the subject witha standard, the level of PKC activity being correlated with the extent,stage, or severity, of the PKC related disorder.
 17. The method of claim16, wherein the disorder is diabetes.
 18. The method of claim 16,wherein the disorder is a cardiovascular disorder.
 19. The method ofclaim 16, wherein the disorder is diabetes mellitus, Type I diabetes,Type II diabetes, diabetic retinopathy, proliferative diabeticretinopathy, non-proliferative diabetic retinopathy, diabeticnephropathy, microalbumiuria, proteinuria, renal failure, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease, valvular disease, arrhythmias, orcardiomyopathy.
 20. The method of claim 16, wherein the PKC activity isPKC β activity.
 21. The method of claim 16, wherein the subject is ahuman.
 22. The method of claim 16, wherein the subject is anexperimental animal.
 23. A method of evaluating the effect of atreatment for a PKC related disorder on a subject comprising:administering a treatment for a PKC related disorder to a subject; andevaluating the level of a PKC activity in monocytes of the subject,thereby evaluating the effect of the treatment.
 24. The method of claim23, wherein the disorder is diabetes.
 25. The method of claim 23,wherein the disorder is a cardiovascular disorder.
 26. The method ofclaim 23, wherein the disorder is diabetes mellitus, Type I diabetes,Type II diabetes, diabetic retinopathy, proliferative diabeticretinopathy, non-proliferative diabetic retinopathy, diabeticnephropathy, microalbumiuria, proteinuria, renal failure, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease, valvular disease, arrhythmias, orcardiomyopathy.
 27. The method of claim 23, wherein the PKC activity isPKC β activity.
 28. The method of claim 23, wherein the subject is ahuman.
 29. The method of claim 23, wherein the subject is anexperimental animal.
 30. A method of identifying a compound for thetreatment of a PKC related disorder in a subject, the method comprising:administering a test compound for the treatment of the disorder to thesubject; and evaluating a PKC activity in monocytes of the subject, thelevel of PKC activity being correlated with the effect of the treatmenton the disorder.
 31. The method of claim 30, wherein the disorder isdiabetes.
 32. The method of claim 30, wherein the disorder is acardiovascular disorder.
 33. The method of claim 30, wherein the PKCrelated disorder is diabetes mellitus, Type I diabetes, Type IIdiabetes, diabetic retinopathy, proliferative diabetic retinopathy, nonproliferative diabetic retinopathy, diabetic nephropathy,microalbumiuria, proteinuria, renal failure, hypertension,atherosclerosis, coronary artery spasm, congestive heart failure,coronary artery disease, valvular disease, arrhythmias, orcardiomyopathy.
 34. The method of claim 30, wherein the PKC activity isPKC β activity.
 35. The method of claim 30, further comprising:optionally identifying a subject in need of a treatment for thedisorder; optionally evaluating a PKC activity in monocytes of thesubject; and comparing the PKC activity before the administration of thetest compound to the PKC activity after administration of the testcompound, wherein a compound for the treatment of the disorder isidentified when the PKC activity after the administration of thecompound is altered compared to a standard.
 36. The method of claim 30,wherein the subject is a human.
 37. The method of claim 30, wherein thesubject is an experimental animal.
 38. A method of identifying acompound for the treatment of aging or an aging-related disorder in asubject, the method comprising: administering a test compound for thetreatment of aging or an aging-related disorder to the subject; andevaluating a PKC activity in monocytes of the subject, the level of PKCactivity being correlated with the effect of the treatment on thedisorder.
 39. A method of evaluating the effect of a treatment for agingor an aging-related disorder on a subject comprising: administering atreatment for aging or an aging-related disorder to a subject; andevaluating the level of a PKC activity in monocytes of the subject,thereby evaluating the effect of the treatment.